Low misalignment sensitivity Kerr-lens mode-locked femtosecond Cr/sup 4+/:Forsterite laser for nonlinear microscopy

We optimized a Kerr-lens mode-locked (KLM) femtosecond Cr/sup 4+/:forsterite laser using a five-mirror cavity, taking advantage of its peculiar low misalignment sensitivity and using an effective KLM mapping technique. A simple scanning nonlinear microscope based on this laser source has been developed and second harmonic images of the layered structure of a microchip are presented.